Filter insertion



. tration is very able space in otherwise any mask would be 1mpossible owing Patented Aug..23, 1932' vAcLAv 1103mm! PRAGUE, czncnosnovnim rmrn msnarron no Dra'wing. Application filed Iareh 14,-1929,

In gas warfare various substances are used which, according to their'phy'sical properties, act either firstly in the gaseous, secondly in the liquid, or thi dly in the solid state. Thus in the secondcase it is a question 0 the suspension of fine drops in the air, that is to say of a poisonous mist, in the third case it is a question of the suspension of solid garticles, that is to say a poisonous smoke. rotection against gases and vapoursis relatively easy and reactive substances a chemical charge is made use of and in the case of less re-active substances, absorption either by activated carbon or some other absorptive medium. fl As the vapour or smoke particles show the so-called Brownian molecular movement, they easily penetrate the ordinary filters and attack thehuman organism.

These particles can be removed from the air either by electro-static deposition or by mechanical filtration. Any mechanical fildiilicult to carry out, as particlesof a very small diameter have to be stopipled by the filter, while on the other hand the ter must not oifer any great resistance, violent movement in the to lack of air. In order to reduce the resistance large filters-must be used, so that the'filter insertions against mist or smoke as used at the present time occupy more than half the availthe whole filter. This disadvantage of the mechanical filters is overcome by the present invention by combining the physico-chemical filter with the mechanical filter in such a manner that the mechamcal filter consisting of fibres is carbonized and activated. Example of one method of production:

which is thereupon carbonized in a known in the case of'chemically which in contradistinction stantially of porous Serial 110. 347,186, and in 0lecho s1ovakh 14. me.

compact mass under a 1.000 kg./cm. The is dried at about gether into ashaped ressure of, for example, moulded body so prepared 35 C., and thereupon carbonized at about f 300 C. The filter insertion is then subjected as to activation. The activation consists in first impregnating the filter insertion with an activating substance, e. g. zinc chloride, steam, an acid of phosphorous, -etc., and then heating to about 800 C. Only certain fibres with definite capillaries and of definite thickness are suitable for making filter insertions (e. g. flax 12-30 hemp, 16-40; jute 1723 By this means a filter insertion is'obtained CI to the filter insertions used hitherto (consisting of felt, cellulose or the like). consists entirely orsubactivated carbon and therefore ofiers protection both against poisonous gases and also against mist and smoke. This filter has the advantage that, while being more efiic'ent, it .enables the filter dimensions to be reduced by half or, withthe same dimensions, f the filter the efiiciency 0 action to be increased by more than It should be noted that the filter insertions are prepared directly by this process.

. What I claim is:

Process for producing small dimensions for gas masks to be used in the resultant molded cak -form without comminution, said insertions offering simultaneous protection against poisonous gases, smoke I and mist, said process consisting in cutting vegetable fibres into short pieces, impregnating the fibres with a binder, compressing the mass into a compact -form and thereupon carbonizing and activating the mass. In testimony whereof I have signed my n name to this specification.

filter insertions of 

